1. Field of the Invention
The present invention relates to a digital planetarium apparatus, for example a digital planetarium apparatus which projects a picture of a video projector onto a dome screen. Moreover, the invention relates to a dome picture apparatus which is applicable as a multipurpose image apparatus (for amusement or the like) and which projects a picture over a wide range of a dome screen.
2. Description of Related Art
Digital planetariums have been gradually wide spread in the world, and transition is occurring from the golden era of optical planetariums to the era of digital planetariums. With the digital planetarium, not only the starry sky observed on the earth and the condition observed in the universe but also the surface condition of a heavenly body observed from thereabove and the like can be reproduced. Moreover, for the digital planetarium, a video projector in a DLP® method, a D-ILA® method, or a liquid crystal method is generally adopted, and the one with an aspect ratio of 16 to 9, which has been conventionally 4 to 3, has been widespread following the trends toward higher vision.
Projection methods adopted for a digital planetarium are largely classified into a split projection method and a single lens projection method. A digital planetarium adopting the split projection method, by using a plurality of (for example, 6) video projectors arranged around a dome, projects images of display devices and links together the images to generate a picture covering the entire dome sky (for example, see patent documents 1 and 2). This permits playing an entire sky picture of the starry sky or the like with feeling of devotion and realistic sensation. On the other hand, a digital planetarium adopting the single lens projection method has one video projector at the center of a dome and magnifies a picture with a fish-eye lens fitted thereto to project the picture on the entire dome sky (for example, see patent document 1), and its use is starting to be widespread due to its excellent maintainability.
[Patent Document 1] JP-A-2004-361880
[Patent Document 2] JP-A-2005-31270
The digital planetarium adopting the split projection method, which forms a picture by using a plurality of video projectors, faces difficulty in brightness adjustment of each video projector. Moreover, if the brightness or the like is out of adjustment because of time-dependent change or the like, remarkable discontinuity appears in a picture on the dome, which is visually undesirable to the audience and which is also very difficulty to adjust. On the other hand, the digital planetarium apparatus adopting the single lens projection method faces no such problem, but has difficulty in achieving higher resolution due to its configuration that a picture covering the entire dome sky is projected with one fish-eye lens for one video projector. Further, an image region generated by the digital planetarium is circular shaped; thus, with a recent video projector having an image display surface with an aspect ratio of nearly 16 to 9, the image region is determined by pixels in the short side direction. As a result, a non-image region increases, thus causing a problem of poor projection efficiency.